1. 4-position models may be factory configured as upflow (MU) or downflow (MD).
2. 3-position 150 MBH model available only in upflow/horizontal (UH) configuration.
4. Dimensions "B", "C", "D", and "E" are with duct flanges turned up. "F", "G", "H", & "J" are with flanges flat.
3. All models are supplied with 3" (7.62 cm) vent connections. An installer supplied transition to 4" (10.16 cm) or 5" (12.7 cm) must be used where necessary.